21st Century Demographics: Highs and Lows

At least two billion additional inhabitants, and perhaps closer to three billion more people, can be expected to be added to world population — now at 6.5 billion — over the next five decades, reaching roughly nine billion by 2050.

Nearly all of the world’s future population growth will take place in the less developed regions. The population of the more developed regions, taken as a whole, is expected to remain near its present size of some 1.2 billion inhabitants.
Almost half of the roughly 76 million people added to the world every year will be born in only six countries — India (22%), China (11%), Pakistan (4%), Nigeria (4%), Indonesia (4%) and Bangladesh (3%).

By mid-century, the populations of 51 countries are projected to be smaller than they are today. The Russian Federation will decrease in population the most, losing 31 million, followed by Ukraine (losing 20 million) and Japan (losing 16 million).

The biggest decline in percentage terms will be in Ukraine (43%), Guyana (35%) and Bulgaria (34%).

Fertility levels came down markedly during the 20th century in virtually every corner of the world — and are expected to continue to do so. By 2050, every major region of the world — except Africa — will be at or below replacement level fertility.

Today, 65 countries, accounting for 43% of world population, have fertility at — or below — the replacement level of 2.1 children per woman. As a result, many countries are concerned about population decline and ageing, as well as the social, economic and cultural consequences of very low fertility.

Mortality rates and increased longevity are expected to continue improving in the 21st century. By 2050, the global life expectancy at birth is projected to increase by at least 10 years, reaching around 76 years.

However, the impact of the HIV/AIDS epidemic has worsened in terms of increased morbidity and mortality, with Africa’s mortality lagging behind other regions.

In Sub-Saharan Africa, life expectancy at birth has declined from 62 years in the early 1990s to 48 years today. In Botswana, where HIV prevalence — 36% of adults — is among the highest, life expectancy has dropped from 65 years a generation ago to 37 years today.

Significant progress was achieved in women’s equality during the 20th century — and this process is expected to spread globally through the 21st century. Like men, growing numbers of women are seeking higher education, employment and social identity.

In two-thirds of the OECD countries, the proportion of women with university degrees has doubled over the level a generation ago — with women now receiving more university degrees than men.

In the United States, the proportions of women receiving doctorates and medical and legal degrees were around 10% or less 30 years ago. As of 2005, they are nearly equal to those of men.

The concept of the family has been generally equated with the nuclear family — father, mother and their offspring. Relatively recently, however, definitions of the family proliferated to reflect differing life-styles and circumstances.

The family consisting of a “working father, stay-at-home mom, some children and marriage-till-death-do-us-part” increasingly appears no longer to be the societal norm.

Since the late 1960s, women’s employment has risen in all G7 countries — except in France, where it has remained essentially unchanged. In many of the industrialized countries, one woman out of seven aged 40-44 years is childless.

Divorce has also increased in these countries. In the United States, for example, the proportion of divorced adults tripled over the last few decades, from 3% in 1970 to 10% in 2005.

Population ageing will be even more critical during the 21st century. By mid-century, the proportion of those 65 years or older in the world is expected to roughly double, from 7% to 15%.

In many countries — such as Italy, Japan and Spain — one person out of three is expected to be 65 years or over. Population ageing raises serious questions about the financial viability of pension and health care systems for the elderly.

Prior to 1800, centenarians — those aged 100 or older — are not believed to have lived. Today, the global population of centenarians is about 250,000. By mid-century, the number of centenarians is expected to increase almost fifteen-fold, to 3.7 million people.

Most of the world’s projected population growth over the coming decades will be in urban areas. By 2007, the majority of the world will no longer be rural dwellers — as has been the case throughout human history — but urban dwellers.

In addition, urban areas in less developed regions are expected to double in size over the next three decades, growing from 1.9 billion people today to 3.9 billion people by 2030.

Also noteworthy in this context is the emergence of very large cities, or mega-cities, with populations of ten million or more. In 1950, New York — with 12.3 million inhabitants — was the only city in this category. By 1975, the number increased to five: Tokyo, New York, Shanghai, Mexico City and Sao Paulo.

Today, there are 19 mega-cities. By 2015, the number is projected to increase by four — with all the newcomers located in Asia.

The more developed regions are expected to continue being net receivers of international migrants, with an average gain of about two million per year over the next 50 years.

The outflow of the highly skilled and educated — the “brain drain” — from the less developed countries, particularly Africa, is likely to further challenge and undercut developmental efforts in many of these countries.

It is estimated that more than half of known graduates from the world’s poorest nations are living abroad. About one-third of R&D professionals from developing countries are estimated to be residing in OECD countries.

From Africa, some 300,000 professionals live and work in Europe and North America. It is estimated that about one-third of the university graduates from Uganda, Tanzania and Kenya are currently living abroad.

In addition to playing an increasingly important demographic role in the 21st century, the increased numbers and flows of migrants will also have significant social, economic, political and cultural consequences.

The expected consequences of the population changes that the world is passing through are profound, affecting virtually every aspect of human society.

Population issues will continue to require sustained and critical attention and informed policy making at the national, regional and global levels. The decisions and actions taken today will affect not only human well-being, but also the quality of all life on the planet in the coming decades and beyond.